Within Cardamine parviflora, in the broad sense, two species or varieties have been recognized: the Eurasian C. parviflora (or C. parviflora var. parviflora) versus the North American C. arenicola (or C. parviflora var. arenicola). Nuclear DNA data suggested a sister relationship of the North American and Eurasian entities, while cpDNA data showed them intermingled (J. Lihová et al. 2006). There are no apparent morphological differences between these entities, although detailed morphological studies are still lacking. We currently prefer to treat them as a single taxon.